The present invention relates to methods for producing intergeneric hybrid plants from crosses between Zinnia elegans and Tagetes erecta and to the plants produced by the methods. All publications cited in this application are herein incorporated by reference.
Zinnia is a genus of plants of the sunflower tribe within the daisy family, Asteraceae, containing approximately 23 different species. Zinnias are annuals, shrubs, and sub-shrubs native to scrub and dry grassland areas in North America, with some species in Central and South America. Zinnia are popular garden flowers that are recognized for their solitary, long-stemmed flowers having a range of appearances that come in a variety of bright colors and ability to withstand hot summer temperatures.
Zinnia elegans, also known as Zinnia violacea, common zinnia or elegant zinnia, is the most familiar zinnia species. Z. elegans is an annual flowering plant native to Mexico, but grown as an ornamental plant and naturalised in many places. There are hundreds of Z. elegans cultivars available that come in many different sizes, forms and flower colors, such as red, yellow, orange, pink, rose, lavender, green and white. The solitary flower heads are typically about two inches across, although there are giant forms up to six inches across, with the purple ray florets surrounding black and yellow discs and lanceolate leaves opposite the flower heads. Z. elegans are susceptible to powdery mildew, particularly in humid climates, as well as to bacterial and fungal leaf and flower spot, as well as alternaria blight.
Tagetes is a genus of mostly herbaceous plants in the daisy family, Asteraceae, containing approximately 50 different species usually known as marigolds. Tagetes are annuals or perennials native to North and South America, with some species having become naturalized around the world. The flowers of Tagetes naturally occur in golden, orange, yellow, and white colors, sometimes with maroon highlights. Most species have pinnate green leaves, and many species have foliage with a musky, pungent scent that is said to deter some common insect pests and nematodes. Marigolds produce a substance called alpha-terthienyl, which can aid in the reduction of root-knot nematodes and other disease promoting organisms, such as fungi, bacteria, insects and some viruses. Marigolds are often used as companion plants in gardens to repel insect pests from neighboring plants.
Tagetes erecta, also known as African marigold, Mexican marigold, Aztec marigold, American marigold and big marigold, is an annual flowering plant native to Mexico and Central America. Mexican marigolds are tall, erect-growing plants up to four feet in height with large, globe-shaped flowers of two to four inches diameter in shades primarily of yellow and orange. T. erecta is a medicinal and ornamental plant and is used for its nematocide, cosmetic and medicinal properties. The essential oil of the T. erecta flower contains antioxidants and is used as a nutritional supplement. Additionally, the florets of T. erecta are rich in the orange-yellow carotenoid lutein and are used as a food color. T. erecta is widely cultivated commercially with many cultivars in use as ornamental plants and for the cut-flower trade.
Interspecific hybridization has been carried out in cultivated plants as a means to increase genetic variability and introduce valuable traits of one species into another. Interspecific hybridization is considered to be one of the most useful strategies to develop new cultivars. However, there are natural processes that ensure reproductive isolation of distinct species, and the ability of any two species to create viable interspecific hybrid seeds or plants is unpredictable and often has proved impossible. Rare interspecific hybrids have been produced from Z. elegans×Z. angustifolia, but embryo culture had to be employed and the hybrids were sterile. Interspecific hybrids between T. erecta and T. patula (French marigold) are available, but result in a sterile, triploid plant that is unable to reproduce.
Intergeneric hybridization, the crossing of two plants from different genera, is more uncommon, unpredictable and improbable than interspecific hybridization because the genetic distance is greater between genera than between species. Only a few successful intergeneric hybrids have been reported and they are frequently only possible through human intervention and the use of embryo rescue.
Thus, it is desirable to create new hybrids having novel characteristics. The present invention provides intergeneric hybrid plants of Z. elegans and T. erecta and methods for creating intergeneric hybrid plants of Z. elegans and T. erecta having more varied color and improved plant habit, improved disease resistance, summer performance and heat tolerance, as well as other desirable characteristics. Prior to the present invention, there have been no previous reports of hybridization between Zinnia spp. and Tagetes spp.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification.